A general method to achieve high magnetization in an interior permanent magnet synchronous motor is to increase both the axial length (rotor stack thickness) of a rotor core and the axial length (stator stack thickness) of a stator core. However, in such a configuration, the used amount of copper, iron, and magnet, which are basic constituent materials of the motor, increases to cause a cost increase, which is not preferable. In a conventional interior permanent magnet synchronous motor represented by Patent Literature 1 mentioned below, the rotor stack thickness is formed larger than the stator stack thickness (to overhang the stator). Therefore, the direct material cost includes only the iron and magnet that constitute a rotor, thereby enabling to suppress the manufacturing cost. Furthermore, in the conventional technique, a magnetic flux generated from an outer periphery of a permanent magnet provided in a portion (an overhanging portion) extending in the axial direction of the rotor core passes a magnetic pole section of the rotor in the overhanging portion and acts on the stator core as an effective magnetic flux, and thus the efficiency is improved.